My height & weight: 6', 250lbs, 38-40" waist.
Equipment: Logitech G27 wheel & Shifter, Fanatec ClubSport V2 pedals
Simply put, I fit perfectly. Getting in is a bit tricky as I can't lift my wheel out of the way completely due to my L-shaped desk, but once in place, and after a quick... umm... adjustment... this is one of the most comfortable seats I have ever used. I was a little worried about how well I'd fit as I'm a big guy, but the seat was easy to adjust and I fit just fine. If you have larger than a 40" waist I'd imagine things could get a bit tricky. Below 40", you're going to fit perfectly. On to some long-winded thoughts:
Build Quality: This is a very sturdy unit. People on gaming forums and people who own dedicated cockpit rigs tend to laugh at it and call it a glorified lawn chair, but it really is a well-built, well-thought out unit. The seat material is a quality, padded ultrasuede type material with nice red stitching. The tubing is solid with a nice matte black powdercoat finish. Once everything is set in place and you are locked in the seat doesn't wobble, tilt, or do anything other than hold you comfortably in place.
Assembly/Adjustment: The instructions are vague, but there really isn't much to do in the way of assembly. Very easy. Once assembled the unit is rather simple to adjust. The seat adjustments are done via adjusting the various Velcro straps that control lumbar support, thigh support, and the angle of the seat back. Unfortunately the wheel mount is only tilt adjustable. It is not height adjustable and does not telescope. That said, it would not be difficult to modify this unit to your liking (especially if you need more height, or need it a little farther away from you) by cutting the tubing and welding in additional sections, or cutting out some and welding or clamping the unit back together. But I suspect if you need that level of adjustment you're going to spring for a dedicated rig.
Pedals: This is where things got tricky for me. It's easy to mount the G27 pedals to the pedal base with the supplied strap, but the Fanatec ClubSport V2 pedals require a custom base to mount. I bolted mine to two sections of 14x6x1 whitewood, then removed the foam padding from the Playseat pedal base and used ½" pipe clamps to secure it. This worked like a charm, and the pedals are extremely stable. The pedal base is not height adjustable, so if you want to angle your pedals you will need to build an angled base - I tried putting some extra boards underneath the end, but this was not very stable and puts undue stress on the two plastic clips that hold the pedal base to the seat. The base really needs to be flat on the ground.
Shifter Mount: As has been mentioned by other reviewers, there is no supplied shifter mount bracket. Instead of paying for the Playseat mount, I used a section of ½" box aluminum and used the G27 wheel clamps to secure it in place. I clamped the G27 shifter to the box aluminum rail and voila... a sub $5 shifter mount that works very well.
Storage: The main reason I bought the Challenge is because I live in an apartment and don't want to have a dedicated cockpit in the way all of the time. The Challenge is very easy to fold up and store away in a closet or against a wall somewhere. Because I have the Fanatec ClubSport V2 pedals on a custom mount, I disconnect the pedal base and leave it under my desk. I fold the seat like you see in the pictures and tuck it away in a closet. Very easy.
Complaints: Less of a complaint but more of an observation - the seat is a bit on the low side. My desk is 28.5" high, so when I get the seat in position my monitors are maybe 2-3" higher than where I'd prefer them. Not really a big deal in the grand scheme of things as I can work around it with view adjustments in iRacing.
Final Thoughts: This is the perfect solution for the casual racer that wants to set up a rig in front of their TV on occasions, or for the hardcore iRacers like me that just don't want to have a dedicated rig due to space concerns. Don't let the forum jokers and non-believers sway you, the Playseat Challenge is FAR from glorified lawn-chair!